CN113376814B

CN113376814B - Optical system, lens module and electronic equipment

Info

Publication number: CN113376814B
Application number: CN202110936429.1A
Authority: CN
Inventors: 党绪文; 刘彬彬; 李明
Original assignee: Jiangxi Jingchao Optical Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2021-08-16
Filing date: 2021-08-16
Publication date: 2021-11-30
Anticipated expiration: 2041-08-16
Also published as: CN113376814A

Abstract

The application discloses an optical system, a lens module and an electronic device, wherein the optical system comprises a first lens with refractive power, a second lens with positive refractive power, a third lens with refractive power, a fourth lens with refractive power, a fifth lens with negative refractive power, a sixth lens with positive refractive power and a seventh lens with refractive power which are sequentially arranged from an object side to an image side along an optical axis. By establishing a 7-piece structure and matching the surface shape and the bending force of each lens, the total optical length is favorably shortened, the compactness of an optical system is improved, a reasonable back focus and a wide visual angle are kept, and excellent image quality is obtained. And the optical system is set to satisfy the conditional expression 1.0 < | R11/R22 |. FNO < 1.56, wherein R11 is the curvature radius of the object side surface of the first lens at the optical axis, R22 is the curvature radius of the image side surface of the second lens at the optical axis, and FNO is the f-number of the optical system, which is beneficial to increasing the aperture, increasing the adaptability of the optical system to large-angle light rays and correcting the edge field image.

Description

Optical system, lens module and electronic equipment

Technical Field

The application relates to the technical field of camera shooting, in particular to an optical system, a lens module and electronic equipment.

Background

With the development of science and technology and the popularization of smart phones and smart electronic devices, devices with diversified camera shooting functions are widely favored by people. The portability requirement of the mobile device is improved, higher requirements are provided for the size of the optical lens group, and in addition, the improvement of the imaging quality becomes a necessary development trend. With the development of electronic devices toward miniaturization, the size of the optical lens assembly is reduced, which reduces the number of lens structures, resulting in insufficient light input and poor resolution. Therefore, how to adjust the balance between the size of the optical lens group and the imaging quality is an important technical problem to be solved by the related technical people.

Disclosure of Invention

The application provides an optical system, a lens module and electronic equipment to solve the balance problem between the size of the optical system and the imaging quality.

In a first aspect, the present application provides an optical system comprising, in order from an object side to an image side along an optical axis:

a first lens element with refractive power;

a second lens element with positive refractive power having a convex object-side surface at paraxial region;

a third lens element with refractive power;

a fourth lens element with refractive power;

a fifth lens element with negative refractive power having a concave object-side surface at paraxial region;

a sixth lens element with positive refractive power having a convex image-side surface in the vicinity of the circumference;

a seventh lens element with refractive power having a convex object-side surface at paraxial region;

the optical system further satisfies the conditional expression: (1) 1.0 < | R11/R22 |. FNO < 1.56, wherein R11 is the radius of curvature of the object-side surface of the first lens at the optical axis, R22 is the radius of curvature of the image-side surface of the second lens at the optical axis, and FNO is the f-number of the optical system.

The second lens has positive refractive power, which is beneficial to shortening the total optical length of the optical system, compressing the light trend of each field of view, reducing spherical aberration and meeting the requirement of high image quality miniaturization of the optical system. The object-side surface of the second lens element is convex near the paraxial region, which is beneficial to enhancing the positive refractive power of the second lens element, providing a reasonable light incidence angle for the introduction of marginal light rays, and increasing the thickness of the first lens element. The fifth lens has negative refractive power, and is beneficial to converging central field light rays and contracting the aperture of marginal field light beams. The object-image side surface of the fifth lens element is concave at the paraxial region, which is beneficial to enhancing the refractive power of the fifth lens element, improving the compactness of the lenses, reasonably restricting the curvature radius of the convex surface, and reducing tolerance sensitivity and stray light risk. The sixth lens element with positive refractive power is advantageous for correcting distortion, astigmatism and field curvature, thereby meeting the requirements of low aberration and high image quality. The image side surface of the sixth lens is a convex surface at a position close to the circumference, so that the incident angle of light on the image surface is kept in a reasonable range, and the requirement of a matching angle of a photosensitive element is met. Through the surface shape and the bending force of each lens and the reasonable distribution of the effective focal length of each lens, the optical system can keep reasonable back focus and wide visual angle, the imaging analysis capability of the optical system can be enhanced, the optical total length of the optical system is reduced, and the compactness of the optical system is improved.

Meanwhile, the focal lengths of the first lens and the second lens can be effectively restricted by controlling the effective focal length of the first lens to meet the conditional expression (1), so that the first lens bears smaller focal power, and the characteristics of the aspheric surfaces of the first lens and the second lens are utilized to increase the aperture, increase the adaptability to large-angle light and correct the marginal field image.

The optical system further includes a diaphragm, and the optical system satisfies conditional expression (2): 0 < ET12 SD11 < 0.16, wherein ET12 is the distance from the maximum clear aperture of the image side surface of the first lens to the diaphragm along the direction parallel to the optical axis, and SD11 is the maximum effective half aperture of the object side surface of the first lens.

Under the condition that two parameters of ET12 and SD11 satisfy the above conditional expression (2), the position of the first lens can be effectively constrained, so that the edge of the first lens is as close to the diaphragm as possible, the aperture of the first lens is further effectively controlled, the gap between the first lens and the second lens is effectively compressed, and the wide-angle lens group can also obtain a smaller head size.

The optical system satisfies conditional expression (3): and 2.4 < TTL/f FNO < 2.8, wherein TTL is the distance between the object side surface of the first lens and the imaging surface of the optical system on the optical axis, and f is the effective focal length of the optical system.

Under the condition that the three parameters of TTL, f and FNO meet the conditional expression (3), the size of the optical system is effectively compressed, and the miniaturization characteristic of the lens is ensured.

The optical system satisfies conditional expression (4): and f67/f is more than 0.75 and less than 3.75, wherein f67 is the effective focal length of the sixth lens and the seventh lens, and f is the effective focal length of the optical system.

Under the condition that f67 and f two parameters satisfy above-mentioned conditional expression (4), can reduce tertiary aberration such as spherical aberration, coma, field curvature on the basis, realize the effective control to optical distortion, help realizing the characteristic of the little distortion of wide angle, be favorable to controlling the volume of sixth lens and seventh lens in addition, improve the space utilization of lens, guarantee to satisfy the miniaturized demand of system.

The optical system satisfies conditional expression (5): 0 < SAG62/R62 < 0.55, wherein SAG62 is the rise of the image side of the sixth lens at the maximum clear aperture and R62 is the radius of curvature of the image side of the sixth lens near the optical axis.

By controlling the two parameters of SAG62 and R62 to satisfy the conditional expression (5), the focal power of the sixth lens, the object-side surface of the sixth lens, and the surface shape of the image-side surface of the sixth lens are favorably controlled, the focal powers of the sixth lens and other lenses of the optical imaging system are balanced, aberrations contributed by the lenses are effectively balanced, and the problem of ghost image caused by multiple reflections of light rays inside the lenses due to the small curvature radius of the image-side surface of the sixth lens can be suppressed.

The optical system satisfies conditional expression (6): 0.45 < (ET34+ ET45+ ET56+ ET67)/FFL < 1.15, wherein ET34 is the distance between the maximum clear aperture position of the image side surface of the third lens and the maximum clear aperture position of the object side surface of the fourth lens along the direction parallel to the optical axis, ET45 is the distance between the maximum clear aperture position of the image side surface of the fourth lens and the maximum clear aperture position of the object side surface of the fifth lens along the direction parallel to the optical axis, ET56 is the distance between the maximum clear aperture position of the image side surface of the fifth lens and the maximum clear aperture position of the object side surface of the sixth lens along the direction parallel to the optical axis, ET67 is the distance between the maximum clear aperture position of the image side surface of the sixth lens and the maximum clear aperture position of the object side surface of the seventh lens along the direction parallel to the optical axis, and FFL is the shortest distance between the image side surface of the seventh lens and the imaging surface of the optical system along the direction of the optical axis.

The ET34, the ET45, the ET56, the ET67 and the FFL are controlled to meet the conditional expression (6), so that the edge size between the lenses is favorably reduced, the whole camera lens group is lighter and thinner, the lens assembly arrangement is more compact, the assembly process difficulty is reduced, a spacer ring is prevented from being used between two adjacent lenses, and the cost is favorably reduced; on the other hand, the range of incident light can be reasonably limited, off-axis aberration is reduced, and the resolution of the camera lens group is effectively improved.

The optical system satisfies conditional expression (7): 0.04 < | R21/R32| < 0.38, wherein R21 is the radius of curvature of the object-side surface of the second lens at the optical axis, and R32 is the radius of curvature of the image-side surface of the third lens at the optical axis.

By controlling the second lens and the third lens, R21 and R32 satisfy the conditional expression (7), reasonable focal power distribution can be provided, the curvature radiuses of the second lens and the third lens are effectively controlled, the surface type with gentle change is kept, the aberration of the optical system is reasonably balanced, and the difficulty in the assembly process caused by overlarge focal power difference of all lenses in the optical system is avoided.

The optical system satisfies conditional expression (8): 0.35 < | f3/R32| < 1.18, wherein R32 is the radius of curvature of the image-side surface of the third lens at the optical axis, and f3 is the focal length of the third lens.

The two parameters f3 and R32 satisfy the above conditional expression (8), which is beneficial to controlling the high-level spherical aberration contributed by the third lens, so that the optical imaging system has good imaging quality, and the increase of surface distortion and tolerance sensitivity caused by too small and too large curvature radius of the image side surface of the third lens at the paraxial region is avoided.

In a second aspect, the present application provides a lens module including a photosensitive element and the optical system as described above, wherein the photosensitive element is disposed at an image side of the optical system to receive light of an image formed by the optical system.

Based on the lens module of this application, make the lens module have good formation of image analytic ability through adopting optical system as above to and be favorable to making the lens module obtain the broad visual angle, still can make the lens module have miniaturized structural feature simultaneously, be convenient for install the lens module in less installation space.

In a third aspect, the present application provides an electronic device, which includes a fixing member and the lens module as above, where the lens module is mounted on the fixing member for acquiring an image.

Based on this application's electronic equipment, can reduce the aberration through the installation like above lens module, guarantee the shooting performance at wide visual angle, make electronic equipment have good formation of image quality.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a schematic structural diagram of an optical system according to an embodiment of the present disclosure;

FIG. 2 (A) is a longitudinal spherical aberration diagram of an optical system according to an embodiment of the present application; fig. 2 (B) is a graph of astigmatism of an optical system according to a first embodiment of the present application; fig. 2 (C) is a distortion graph of an optical system according to an embodiment of the present application;

fig. 3 is a schematic structural diagram of an optical system according to a second embodiment of the present application;

fig. 4 (a) is a longitudinal spherical aberration diagram of an optical system according to the second embodiment of the present application; fig. 4 (B) is an astigmatism graph of an optical system according to a second embodiment of the present application; fig. 4 (C) is a distortion graph of an optical system according to the second embodiment of the present application;

fig. 5 is a schematic structural diagram of an optical system according to a third embodiment of the present application;

fig. 6 (a) is a longitudinal spherical aberration diagram of an optical system provided in the third embodiment of the present application; fig. 6 (B) is an astigmatism graph of an optical system according to a third embodiment of the present application; fig. 6 (C) is a distortion graph of an optical system according to a third embodiment of the present application;

fig. 7 is a schematic structural diagram of an optical system according to a fourth embodiment of the present application;

fig. 8 (a) is a longitudinal spherical aberration diagram of an optical system according to the fourth embodiment of the present application; fig. 8 (B) is an astigmatism graph of an optical system according to a fourth embodiment of the present application; fig. 8 (C) is a distortion graph of an optical system according to a fourth embodiment of the present application;

fig. 9 is a schematic structural diagram of an optical system according to a fifth embodiment of the present application;

fig. 10 (a) is a longitudinal spherical aberration diagram of an optical system according to fifth embodiment of the present application; fig. 10 (B) is an astigmatism graph of an optical system according to example five of the present application; fig. 10 (C) is a distortion graph of an optical system according to example five of the present application;

fig. 11 is a schematic structural diagram of an optical system according to a sixth embodiment of the present application;

fig. 12 (a) is a longitudinal spherical aberration diagram of an optical system according to a sixth embodiment of the present application; fig. 12 (B) is an astigmatism graph of an optical system according to a sixth embodiment of the present application; fig. 12 (C) is a distortion graph of an optical system according to a sixth embodiment of the present application;

fig. 13 is a cross-sectional view of a lens module provided in an embodiment of the present application;

fig. 14 is a front view of an electronic device provided in an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

Referring to fig. 1, fig. 3, fig. 5, fig. 7, fig. 9, and fig. 11, which are schematic structural diagrams illustrating an optical system 100 according to an embodiment of the present disclosure, the optical system 100 includes, in order from an object side to an image side along an optical axis H, a first lens element L1, a second lens element L2, a third lens element L3, a fourth lens element L4, a fifth lens element L5, a sixth lens element L6, and a seventh lens element L7, which have refractive power for light rays. When the optical system 100 is used for imaging, light from the object side passes through the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 in sequence and is projected into the imaging plane IMG. The imaging surface IMG can be used for arranging photosensitive elements, light rays passing through the seventh lens L7 can be received by the photosensitive elements in the imaging surface IMG and converted into image signals, and the photosensitive elements transmit the image signals to other rear-end systems for image analysis and other processing.

The first lens L1 has a bending force, which is beneficial to ensure that the first lens L1 has sufficient light converging capability.

The second lens L2 has positive bending force, which is helpful to shorten the total optical length of the optical system 100, compress the light direction of each field of view, reduce spherical aberration, and meet the requirement of miniaturization of the optical system 100 with high image quality. In addition, the object-side surface S3 of the second lens element L2 is convex near the paraxial region H, which is favorable for enhancing the positive refractive power of the second lens element L2, further providing a reasonable incident angle for the marginal rays, and is favorable for increasing the thickness of the first lens element L1.

The third lens L3 has a bending force, and the third lens L3 surface type and the front end lens surface type can be combined to further coordinate the light propagation angle, delay the wide angle, reduce the sensitivity of the optical system 100, reduce the distortion, and improve the imaging analysis capability of the optical system 100.

The fourth lens element L4 has a bending force, and can flexibly set the surface shape of the fourth lens element L4 and the surface shape of the front lens element to coordinate the light propagation angle, and help to correct the aberration generated by the front lens element.

The fifth lens L5 has negative bending force, which is beneficial to converging central field light and shrinking the aperture of edge field light beam. The image-side surface S10 of the fifth lens element L5 is concave at a paraxial region H, which is favorable for enhancing the refractive power of the fifth lens element L5, improving the compactness of the lens elements, reasonably restricting the curvature radius of the convex surface, reducing the tolerance sensitivity and the risk of stray light, and improving the imaging quality.

The sixth lens element L6 has positive refractive power, which is beneficial to correcting distortion, astigmatism and field curvature, thereby meeting the requirements of low aberration and high image quality. The image-side surface S12 of the sixth lens element L6 is convex at a position close to the circumference, so that the incident angle of light on the image plane IMG can be kept in a reasonable range, and the requirement of the matching angle of the photosensitive element can be met.

The seventh lens L7 has a bending force, so that the light propagation angle can be adjusted, the marginal light can be incident on the imaging surface IMG conveniently, the aberration can be corrected, and the imaging quality can be improved.

The optical system 100 further satisfies the conditional expression (1): 1.0 < | R11/R22 |. FNO < 1.56, where R11 is the radius of curvature of the object-side surface S1 of the first lens L1 at the optical axis H, R22 is the radius of curvature of the image-side surface S4 of the second lens L2 at the optical axis H, and FNO is the f-number of the optical system 100. The | R11/R22| FNO may be 1.014, 1.120, 1.175, 1.279, 1.502, or 1.550. By controlling the three parameters of R11, R22 and FNO to satisfy the conditional expression (1), the focal lengths of the first lens L1 and the second lens L2 can be effectively restricted, so that the first lens L1 bears smaller focal power, and the aspheric characteristics of the first lens L1 and the second lens L2 are utilized, thereby being beneficial to enlarging the aperture, increasing the adaptability to large-angle light rays and correcting the marginal field image. When the value of | R11/R22 |. FNO is lower than the minimum value of 1.0 in conditional expression (1), the curvature radius of the object-side surface S1 of the first lens L1 is small, which can provide strong focal power and can well collect light rays with large angles, but the phenomena of excessive bending of the surface of the first lens L1 and increase of the aperture are caused, which is difficult to avoid, and the miniaturization of the lens assembly is not facilitated.

In the optical system 100 in the embodiment of the present application, by setting the surface shape and the bending force of each lens and the effective focal length of each lens to be reasonably distributed, distortion, chromatic aberration and the like can be reduced, the imaging quality of the optical system 100 can be improved, and it is beneficial to the optical system 100 to expand the field of view and realize a wider viewing angle, and in addition, by setting the surface shape and the bending force of each lens and the effective focal length of each lens to be reasonably distributed, the optical total length of the optical system 100 can be favorably shortened, and the requirement for miniaturization of the optical system 100 can be satisfied.

In some exemplary embodiments, the optical system 100 further includes a stop ST, and the optical system 100 further satisfies the conditional expression (2): 0 < ET12 × SD11 < 0.16, where ET12 is the distance from the stop ST in the direction parallel to the optical axis H at the maximum clear aperture of the image-side surface S2 of the first lens L1, and SD11 is the maximum effective half aperture of the object-side surface S1 of the first lens L1. ET12 × SD11 may be 0.001, 0.021, 0.025, 0.101, 0.417 or 0.522. By controlling the product of the edge gap between the first lens L1 and the diaphragm ST and the aperture of the object side surface S1 of the first lens L1 to satisfy the conditional expression (2), the position of the first lens L1 can be effectively restrained, the edge of the first lens L1 is enabled to be close to the diaphragm ST as much as possible, the aperture of the first lens L1 is effectively controlled, the optical system 100 is enabled to obtain a smaller head size, the gap between the first lens L1 and the second lens L2 is effectively compressed, and the reduction of the size of a lens module is facilitated.

In some exemplary embodiments, the optical system 100 further satisfies the conditional expression (3): 2.4 < TTL/f FNO < 2.8, where TTL is a distance on the optical axis H from the object-side surface S1 of the first lens element L1 to the image plane IMG of the optical system 100, i.e., a total optical length, and f is an effective focal length of the optical system 100. TTL/f FNO may be 2.432, 2.670, 2.744, 2.746, 2.754 or 2.778. The three parameters of the total optical length TTL, the effective focal length f of the optical system 100 and the f number FNO of the optical system 100 are controlled to meet the conditional expression (3), so that the size of the optical system 100 is effectively reduced, and the miniaturization requirement of a lens is met. When the ratio of the TTL parameter, the f parameter and the FNO parameter exceeds the maximum value of the conditional expression (3) by 2.8, the optical system 100 is large in size, and the f-number is large and cannot meet the requirement of large image surface and small size; when the ratio of the TTL parameter, the f parameter, and the FNO parameter is lower than the minimum value of 2.4 in the conditional expression (3), the design difficulty is high, and it is difficult to optimize the surface type of each lens to reduce the sensitivity, which results in a difficulty in the assembly process of each lens in the optical system 100.

In some exemplary embodiments, the optical system 100 further satisfies the conditional expression (4): 0.75 < f67/f < 3.75, wherein f67 is the combined effective focal length of the sixth lens L6 and the seventh lens L7, and f is the effective focal length of the optical system 100. f67/f can be 0.793, 0.799, 1.568, 1.864, 2.212, or 3.693. Satisfy above-mentioned conditional expression (4) through the combined focal length of controlling sixth lens L6 and seventh lens L7, the focal power of rational distribution sixth lens L6 and seventh lens L7, avoid appearing less positive focal power, reduce on the basis of tertiary aberration such as spherical aberration, coma, curvature of field, in addition, be favorable to controlling the volume of sixth lens L6 and seventh lens L7, help realizing the characteristic of the little distortion of wide angle, improve the space utilization of lens, guarantee to satisfy optical system 100 miniaturization demand.

In some exemplary embodiments, the optical system 100 further satisfies the conditional expression (5): 0 < SAG62/R62 < 0.55, wherein SAG62 is the rise of the image-side surface S12 of the sixth lens L6 at the maximum clear aperture, and when SAG62 has a positive value, the maximum effective clear aperture of the image-side surface S12 of the sixth lens L6 is closer to the object side of the optical system 100 than the center of the surface in the direction parallel to the optical axis H of the optical system 100; when the SAG62 value is a negative value, the maximum effective clear aperture of the image-side surface S12 of the sixth lens L6 is closer to the image side of the optical system 100 than the center of the surface in a direction parallel to the optical axis H of the optical system 100; r62 is the radius of curvature of the image-side surface S12 of the sixth lens element L6 near the optical axis H. SAG62/R62 can be 0.001, 0.163, 0.232, 0.453, 0.454, or 0.538. By controlling two parameters of SAG62 and R62 to satisfy the conditional expression (5), the focal power of the sixth lens L6 and the surface shapes of the object-side surface S11 of the sixth lens L6 and the image-side surface S12 of the sixth lens L6 are favorably controlled, the focal powers of the sixth lens L6 and the other lenses of the optical system 100 are balanced, aberrations contributed by the lenses are effectively balanced, and the ghost problem caused by multiple reflections of light rays inside the lenses due to the small curvature radius of the image-side surface S12 of the sixth lens L6 is suppressed.

In some exemplary embodiments, the optical system 100 further satisfies conditional expression (6): 0.45 < (ET34+ ET45+ ET56+ ET67)/FFL < 1.15, where ET34 is the distance in the direction parallel to the optical axis H between the maximum clear aperture of the image-side surface S6 of the third lens L3 and the maximum clear aperture of the object-side surface S7 of the fourth lens L4, ET45 is the distance in the direction parallel to the optical axis H between the maximum clear aperture of the image-side surface S8 of the fourth lens L4 and the maximum clear aperture of the object-side surface S9 of the fifth lens L5, ET56 is the distance in the direction parallel to the optical axis H between the maximum clear aperture of the image-side surface S10 of the fifth lens L5 and the maximum clear aperture of the object-side surface S11 of the sixth lens L6, ET67 is the distance in the direction parallel to the optical axis imh between the maximum clear aperture of the image-side surface S12 of the sixth lens L6 and the maximum clear aperture of the object-side surface S12 of the seventh lens L12, and the shortest distance in the optical axis H36100 of the imaging system 12. (ET34+ ET45+ ET56+ ET67)/FFL may be 0.466, 0.592, 0.924, 0.959, 0.821 or 1.143. By controlling the uniform distribution of the bending forces of the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6 and the seventh lens L7, five parameters of ET34, ET45, ET56, ET67 and FFL meet the conditional expression (6), on one hand, the edge size between lenses is favorably reduced, the whole camera lens group is lighter and thinner, the assembly arrangement of the lenses is more compact, the difficulty of the assembly process is reduced, a spacing ring is avoided being used between two adjacent lenses, and the cost is favorably reduced; on the other hand, the range of incident light can be reasonably limited, off-axis aberration is reduced, and the resolution of the camera lens group is effectively improved.

In some exemplary embodiments, the optical system 100 further satisfies the conditional expression (7): 0.04 < | R21/R32| < 0.38, wherein R21 is the radius of curvature of the object-side surface S3 of the second lens L2 at the optical axis H, and R32 is the radius of curvature of the image-side surface S6 of the third lens L3 at the optical axis H. I R21/R32I may be 0.041, 0.054, 0.223, 0.342, 0.347 or 0.379. By reasonably arranging the second lens L2 and the third lens L3 such that the curvature radii near the optical axis H satisfy the conditional expression (7), more reasonable power distribution can be provided, the curvature radii of the second lens L2 and the third lens L3 can be effectively controlled, the surface shape with gentle change can be maintained, the aberration of the optical system 100 can be reasonably balanced, and the difficulty in the assembly process caused by the excessively large difference of the power of each lens in the optical system 100 can be avoided.

In some exemplary embodiments, the optical system 100 further satisfies the conditional expression (8): 0.35 < | f3/R32| < 1.18, wherein R32 is the radius of curvature of the image-side surface S6 of the third lens L3 at the optical axis H, and f3 is the focal length of the third lens L3. If 3/R32 can be 0.172, 0.391, 0.625, 0.959, 0.971, or 1.141. By controlling the two parameters f3 and R32 to satisfy the above conditional expression (8), the effective focal length and the radius of curvature of the image-side surface of the third lens L3 are kept within a reasonable range, which is beneficial to controlling the high-level spherical aberration contributed by the third lens L3, so that the optical system 100 has good imaging quality, and avoids the increase of the surface distortion and tolerance sensitivity caused by the excessively small radius of curvature of the image-side surface S6 of the third lens L3 at the paraxial region H.

In some exemplary embodiments, the object-side surface and/or the image-side surface of the first lens element L1 through the seventh lens element L7 may be aspheric, and the aspheric design enables the object-side surface and/or the image-side surface of the lens elements to have a more flexible design, so that the lens elements can solve the problems of poor imaging performance, distortion of the field of view and the like in a small and thin size, and the lens group can have good imaging quality without providing too many lens elements, and the length of the optical system 100 can be shortened. The aberration of the system can be effectively eliminated by the cooperation of the aspheric lenses, so that the optical system 100 has good imaging quality, and the flexibility of the design and assembly of the lenses in the optical system 100 is improved.

The material of each lens in the optical system 100 may be plastic, glass, or a combination of glass and plastic. The plastic lens can reduce the weight of the optical system 100 and the manufacturing cost, while the glass lens can withstand higher temperature and has excellent optical effects. Specifically, the first lens L1 to the fifth lens L5 may be made of plastic, which facilitates processing of the lenses. Of course, the configuration relationship of the lens materials in the optical system 100 is not limited to the above embodiments, any one of the lenses may be made of plastic or glass, and the specific configuration relationship is determined according to the actual design requirement and will not be described herein.

The optical system 100 further includes a stop ST centered on the optical axis H of the optical system 100, and in particular, in some embodiments, the stop ST may be disposed between the image-side surface S2 of the first lens L1 and the object-side surface S3 of the second lens L2 and mounted with each lens on a barrel, such as a lens barrel. In other embodiments, the stop ST may be provided as a light-shielding layer applied on the object side or the image side of the lens, and leaving a light-transmitting area to allow light to pass through.

The optical system 100 further includes a filter L8, and the filter L8 is disposed between the image-side surface S14 of the seventh lens element L7 and the image plane IMG. The filter L8 may be an ir cut filter for filtering infrared light, and preventing the infrared light from reaching the imaging plane IMG of the optical system 100, so as to prevent the infrared light from interfering with normal imaging. The filter L8 may be assembled with each lens as part of the optical system 100. For example, in some embodiments, each lens in the optical system 100 is mounted in a lens barrel, and the filter L8 is mounted at the image end of the lens barrel. In other embodiments, the filter L8 does not belong to the optical system 100, and the filter L8 may be installed between the optical system 100 and the photosensitive element when the optical system 100 and the photosensitive element are assembled into a camera module. In some embodiments, the optical filter L8 may also be disposed on the object side of the first lens L1. In addition, in some embodiments, the filter L8 may not be provided, and an infrared filter is provided on an object side surface or an image side surface of at least one of the first lens L1 to the seventh lens L7 to filter infrared light.

The optical system 100 of the above embodiment of the present application can adopt a plurality of lenses, and by reasonably distributing the focal length, refractive power, surface shape, thickness of each lens, and the on-axis distance between each lens, it can be ensured that the optical system 100 obtains wide-view shooting performance and better imaging quality, thereby better meeting the application requirements of light-weight electronic devices such as a lens, a mobile phone, and a flat panel of a vehicle-mounted auxiliary system.

The assembly structure and the corresponding implementation result of the optical system 100 according to the present embodiment will be described below with reference to the accompanying drawings and tables, in conjunction with specific numerical values.

The notations shown in the respective embodiments have the meanings as follows.

S1, S3, S5, S7, S9, S11, S13, and S15 are numbers of the object side surface of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the filter L8, respectively, and S2, S4, S6, S8, S10, S12, S14, and S16 are numbers of the image side surface of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the filter L8, respectively.

"K" represents a Conic Constant (Constant), "a 4", "a 6", "A8", … … "and" a20 "represent aspheric coefficients of 4 th order, 6 th order, 8 th order, … … and 20 th order, respectively.

In each table showing conic constants and aspherical coefficients below, numerical values are expressed by an index with a base 10. For example, "0.12E-05" means "0.12 × (minus 5 powers of 10)", and "9.87E + 03" means "9.87 × (3 powers of 10)".

In the optical system 100 used in each embodiment, specifically, when the distance in the direction perpendicular to the optical axis H is "R", the paraxial curvature at the lens origin is "c" (the paraxial curvature c is the inverse of the upper lens curvature radius R, that is, c is 1/R), the conic constant is "K", and the aspherical coefficients of 4 th order, 6 th order, 8 th order, … …, and i th order are "a 4", "a 6", "a 8", … … ", and" Ai ", respectively, the aspherical shape x is defined by the following equation 1.

Mathematical formula 1:

example one

Referring to fig. 1, the optical system 100 in this embodiment includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and a filter L8, which are sequentially disposed from an object side to an image side along an optical axis H, a stop ST is disposed between an image side surface S2 of the first lens L1 and an object side surface S3 of the second lens L2, and an imaging surface IMG of the optical system 100 is located on a side of the filter L8 away from the seventh lens L7. The first lens L1 to the seventh lens L7 are all plastic aspheric lenses, and the filter L8 is an infrared cut filter L8 made of glass.

The first lens element L1 with positive refractive power has a concave object-side surface S1 at a paraxial region H and a convex image-side surface S2 at a paraxial region H of the first lens element L1, and has a concave object-side surface S1 at a circumference and a convex image-side surface S2 at a circumference of the first lens element L1.

The second lens element L2 with positive refractive power has a convex object-side surface S3 at the paraxial region H and a concave image-side surface S4 at the paraxial region H of the second lens element L2, and has a convex object-side surface S3 and a concave image-side surface S4 at the periphery of the second lens element L2.

The third lens element L3 with positive refractive power has a convex object-side surface S5 and an convex image-side surface S6 at a paraxial region H of the third lens element L3, a concave object-side surface S5 of the third lens element L3, and a convex image-side surface S6.

The fourth lens element L4 with negative refractive power has a concave object-side surface S7 and an concave image-side surface S8 at paraxial region H of the fourth lens element L4, and has a concave object-side surface S7 and a concave image-side surface S8 at periphery of the fourth lens element L4.

The fifth lens element L5 with negative refractive power has a concave object-side surface S9 at the paraxial region H and a convex image-side surface S10 at the paraxial region H of the fifth lens element L5, and has a concave object-side surface S9 and a convex image-side surface S10 at the periphery of the fifth lens element L5.

The sixth lens element L6 with positive refractive power has a concave object-side surface S11 at a paraxial region H and a convex image-side surface S12 at a paraxial region H of the sixth lens element L6, and has a concave object-side surface S11 and a convex image-side surface S12 at a circumference of the sixth lens element L6.

The seventh lens element L7 with negative refractive power has a convex object-side surface S13 at the paraxial region H and a concave image-side surface S14 at the paraxial region H of the seventh lens element L7, and has a concave object-side surface S13 and a convex image-side surface S14 at the periphery of the seventh lens element L7.

In the first embodiment, the focal length, refractive index and abbe number of the optical system 100 are all referenced to light with a wavelength of 587.00nm, and relevant parameters of the optical system 100 are shown in table 1. Where f is the effective focal length of the optical system 100, FNO represents the aperture value, FOV represents the maximum field angle of the optical system 100, TTL represents the total optical length of the optical system 100, and the units of the curvature radius, thickness, and focal length are all millimeters.

TABLE 1

The numerical relationship calculation results of the parameters of the optical system 100 in this embodiment are shown in table 2.

TABLE 2

As can be seen from the results in table 2, the calculation results of the numerical relationships between the lens-related parameters of the optical system 100 in the present embodiment satisfy the conditional expressions (1) to (8) in a one-to-one correspondence.

The conic constant K and aspheric coefficients corresponding to the surfaces of the lenses in the first example are shown in table 3.

TABLE 3

Fig. 2 (a), 2 (B) and 2 (C) are a longitudinal spherical aberration graph, an astigmatism graph and a distortion graph, respectively, in the first embodiment.

The abscissa of the vertical spherical aberration graph represents the focus shift, and the ordinate represents the normalized field of view, and when the wavelengths given in (a) of fig. 2 are 650.0000nm, 610.0000nm, 587.0000nm, 555.0000, and 470.0000, respectively, the focus shifts of different fields of view are all within ± 0.05 mm, which illustrates that the optical system 100 in this embodiment has a small vertical spherical aberration and good imaging quality.

The abscissa of the astigmatism graph indicates the focus offset, the ordinate indicates the image height, and the astigmatism curve given in (B) of fig. 2 indicates that the focus offsets of the sagittal image plane and the meridional image plane are within ± 0.05 mm at a wavelength of 587.0000nm, which indicates that the optical system 100 in this embodiment has less astigmatism and better imaging quality.

The abscissa of the distortion graph represents the distortion rate, the ordinate represents the image height, and the distortion curve given in (C) of fig. 2 represents that the distortion is within ± 5% at a wavelength of 587.0000nm, which shows that the distortion of the optical system 100 in this embodiment is better corrected and the imaging quality is better.

As can be seen from fig. 2 (a), 2 (B), and 2 (C), the optical system 100 according to the first embodiment can achieve a good imaging effect.

Example two

Referring to fig. 3, the optical system 100 in this embodiment includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and a filter L8, which are sequentially disposed from an object side to an image side along an optical axis H, a stop ST is disposed between an image side surface S2 of the first lens L1 and an object side surface S3 of the second lens L2, and an imaging surface IMG of the optical system 100 is located on a side of the filter L8 away from the seventh lens L7. The first lens L1 to the seventh lens L7 are all plastic aspheric lenses, and the filter L8 is an infrared cut filter L8 made of glass.

The first lens element L1 with positive refractive power has a concave object-side surface S1 at a paraxial region H and a convex image-side surface S2 at a paraxial region H of the first lens element L1, and the object-side surface S1 and the image-side surface S2 of the first lens element L1 are both concave on their circumferences.

The second lens element L2 with positive refractive power has a convex object-side surface S3 at the paraxial region H and a concave image-side surface S4 at the paraxial region H of the second lens element L2, and has convex object-side surface S3 and convex image-side surface S4 at the circumference of the second lens element L2.

The fourth lens element L4 with negative refractive power has a concave object-side surface S7 and an image-side surface S8 at a paraxial region H of the fourth lens element L4, a circumferentially concave object-side surface S7 and a circumferentially convex image-side surface S8 of the fourth lens element L4.

The sixth lens element L6 with positive refractive power has a convex object-side surface S11 and an convex image-side surface S12 at a paraxial region H of the sixth lens element L6, a concave object-side surface S11 of the sixth lens element L6, and a convex image-side surface S12.

In the second embodiment, the focal length, refractive index and abbe number of the optical system 100 are all referenced to the light ray with the wavelength of 587.00nm, and the relevant parameters of the optical system 100 are shown in table 4. Where f is the effective focal length of the optical system 100, FNO represents the aperture value, FOV represents the maximum field angle of the optical system 100, TTL represents the total optical length of the optical system 100, and the units of the curvature radius, thickness, and focal length are all millimeters.

TABLE 4

The numerical relationship calculation results of the parameters of the optical system 100 in this embodiment are shown in table 5.

TABLE 5

As can be seen from the results in table 5, the calculation results of the numerical relationships between the lens-related parameters of the optical system 100 in the present embodiment satisfy the conditional expressions (1) to (8) in a one-to-one correspondence.

The conic constant K and aspheric coefficients corresponding to the surfaces of the lenses in example two are shown in table 6.

TABLE 6

Fig. 4 (a), 4 (B) and 4 (C) are a longitudinal spherical aberration graph, an astigmatism graph and a distortion graph, respectively, in the second embodiment.

The abscissa of the vertical spherical aberration graph represents the focus shift and the ordinate represents the normalized field of view, and when the wavelengths given in (a) of fig. 4 are 650.0000nm, 610.0000nm, 587.0000nm, 555.0000, and 470.0000, respectively, the focus shifts of different fields of view are all within ± 0.025 mm, which illustrates that the optical system 100 in this embodiment has a small vertical spherical aberration and good imaging quality.

The abscissa of the astigmatism graph indicates the focus offset, the ordinate indicates the image height, and the astigmatism curve given in (B) of fig. 4 indicates that the focus offsets of the sagittal image plane and the meridional image plane are within ± 0.20 mm when the wavelength is 587.0000nm, which indicates that the optical system 100 in this embodiment has less astigmatism and better imaging quality.

The abscissa of the distortion graph represents the distortion rate, the ordinate represents the image height, and the distortion curve given in (C) of fig. 4 represents that the distortion is within ± 5% at a wavelength of 587.0000nm, which shows that the distortion of the optical system 100 in this embodiment is better corrected and the imaging quality is better.

As can be seen from fig. 4 (a), 4 (B), and 4 (C), the optical system 100 according to the second embodiment can achieve a good imaging effect.

EXAMPLE III

Referring to fig. 5, the optical system 100 in this embodiment includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and a filter L8, which are sequentially disposed from an object side to an image side along an optical axis H, a stop ST is disposed between an image side surface S2 of the first lens L1 and an object side surface S3 of the second lens L2, and an imaging surface IMG of the optical system 100 is located on a side of the filter L8 away from the seventh lens L7. The first lens L1 to the seventh lens L7 are all plastic aspheric lenses, and the filter L8 is an infrared cut filter L8 made of glass.

The first lens element L1 with positive refractive power has a convex object-side surface S1 at a paraxial region H and a concave image-side surface S2 at a paraxial region H of the first lens element L1, and has a convex object-side surface S1 and a concave image-side surface S2 at a circumference of the first lens element L1.

The third lens element L3 with negative refractive power has a concave object-side surface S5 at the paraxial region H, a convex image-side surface S6 at the paraxial region H, and a concave object-side surface S5 and a concave image-side surface S6 of the third lens element L3.

The fourth lens element L4 with positive refractive power has a convex object-side surface S7 and an image-side surface S8 at a paraxial region H of the fourth lens element L4, and has a convex object-side surface S7 and an image-side surface S8 at a circumference of the fourth lens element L4.

The fifth lens element L5 with negative refractive power has a concave object-side surface S9 and an concave image-side surface S10 at paraxial region H of the fifth lens element L5, and has a concave object-side surface S9 and a concave image-side surface S10 at periphery of the fifth lens element L5.

In the third embodiment, the focal length, refractive index and abbe number of the optical system 100 are all referenced to the light ray with the wavelength of 587.00nm, and the relevant parameters of the optical system 100 are shown in table 7. Where f is the effective focal length of the optical system 100, FNO represents the aperture value, FOV represents the maximum field angle of the optical system 100, TTL represents the total optical length of the optical system 100, and the units of the curvature radius, thickness, and focal length are all millimeters.

TABLE 7

The numerical relationship calculation results of the parameters of the optical system 100 in this embodiment are shown in table 8.

TABLE 8

As can be seen from the results in table 8, the calculation results of the numerical relationships between the lens-related parameters of the optical system 100 in this embodiment satisfy the conditional expressions (1) to (8) in a one-to-one correspondence.

The conic constant K and aspherical surface coefficients corresponding to the surfaces of the lenses in example three are shown in table 9.

TABLE 9

Fig. 6 (a), 6 (B), and 6 (C) are a longitudinal spherical aberration graph, an astigmatism graph, and a distortion graph, respectively, in the third embodiment.

The abscissa of the vertical spherical aberration graph represents the focus shift, and the ordinate represents the normalized field of view, and when the wavelengths given in (a) in fig. 6 are 650.0000nm, 610.0000nm, 587.0000nm, 555.0000, and 470.0000, respectively, the focus shifts of different fields of view are all within ± 0.05 mm, which illustrates that the optical system 100 in this embodiment has a small vertical spherical aberration and good imaging quality.

The abscissa of the astigmatism graph indicates the focus offset, the ordinate indicates the image height, and the astigmatism curve given in (B) of fig. 6 indicates that the focus offsets of the sagittal image plane and the meridional image plane are within ± 0.75 mm at a wavelength of 587.0000nm, which indicates that the optical system 100 in this embodiment has less astigmatism and better imaging quality.

The abscissa of the distortion graph represents the distortion rate, the ordinate represents the image height, and the distortion curve given in (C) of fig. 6 represents that the distortion is within ± 5% at a wavelength of 587.0000nm, which shows that the distortion of the optical system 100 in this embodiment is better corrected and the imaging quality is better.

As can be seen from fig. 6 (a), 6 (B), and 6 (C), the optical system 100 according to the third embodiment can achieve a good imaging effect.

Example four

Referring to fig. 7, the optical system 100 in this embodiment includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and a filter L8, which are sequentially disposed from an object side to an image side along an optical axis H, a stop ST is disposed between an image side surface S2 of the first lens L1 and an object side surface S3 of the second lens L2, and an imaging surface IMG of the optical system 100 is located on a side of the filter L8 away from the seventh lens L7. The first lens L1 to the seventh lens L7 are all plastic aspheric lenses, and the filter L8 is an infrared cut filter L8 made of glass.

The third lens element L3 with negative refractive power has a concave object-side surface S5 and an image-side surface S6 at a paraxial region H of the third lens element L3, a circumferentially concave object-side surface S5 and a circumferentially convex image-side surface S6 of the third lens element L3.

The fourth lens element L4 with positive refractive power has a convex object-side surface S7 and an convex image-side surface S8 at a paraxial region H of the fourth lens element L4, a concave object-side surface S7 of the fourth lens element L4, and a convex image-side surface S8.

The fifth lens element L5 with negative refractive power has a concave object-side surface S9 and an image-side surface S10 at a paraxial region H of the fifth lens element L5, a circumferentially concave object-side surface S9 and a circumferentially convex image-side surface S10 of the fifth lens element L5.

The seventh lens element L7 with negative refractive power has a convex object-side surface S13 at the paraxial region H and a concave image-side surface S14 at the paraxial region H of the seventh lens element L7, and both the object-side surface S13 and the image-side surface S14 of the seventh lens element L7 are circumferentially convex.

In the fourth embodiment, the focal length, refractive index and abbe number of the optical system 100 are all referenced to the light ray with the wavelength of 587.00nm, and the relevant parameters of the optical system 100 are shown in table 10. Where f is the effective focal length of the optical system 100, FNO represents the aperture value, FOV represents the maximum field angle of the optical system 100, TTL represents the total optical length of the optical system 100, and the units of the curvature radius, thickness, and focal length are all millimeters.

Watch 10

The numerical relationship calculation results of the parameters of the optical system 100 in this embodiment are shown in table 11.

TABLE 11

As can be seen from the results in table 11, the calculation results of the numerical relationships between the lens-related parameters of the optical system 100 in the present embodiment satisfy the conditional expressions (1) to (8) in a one-to-one correspondence.

The conic constant K and aspherical surface coefficients corresponding to the surfaces of the respective lenses in example four are shown in table 12.

TABLE 12

Fig. 8 (a), 8 (B) and 8 (C) are a longitudinal spherical aberration graph, an astigmatism graph and a distortion graph, respectively, in the fourth embodiment.

The abscissa of the vertical spherical aberration graph represents the focus shift, and the ordinate represents the normalized field of view, and when the wavelengths given in (a) of fig. 8 are 650.0000nm, 610.0000nm, 587.0000nm, 555.0000, and 470.0000, respectively, the focus shifts of different fields of view are all within ± 0.05 mm, which illustrates that the optical system 100 in this embodiment has a small vertical spherical aberration and good imaging quality.

The abscissa of the astigmatism graph indicates the focus offset, the ordinate indicates the image height, and the astigmatism curve given in (B) of fig. 8 indicates that the focus offsets of the sagittal image plane and the meridional image plane are within ± 0.4 mm at a wavelength of 587.0000nm, which indicates that the optical system 100 in this embodiment has less astigmatism and better imaging quality.

The abscissa of the distortion graph represents the distortion rate, the ordinate represents the image height, and the distortion curve given in (C) of fig. 8 represents that the distortion is within ± 5% at a wavelength of 587.0000nm, which shows that the distortion of the optical system 100 in this embodiment is better corrected and the imaging quality is better.

As can be seen from fig. 8 (a), 8 (B), and 8 (C), the optical system 100 according to the fourth embodiment can achieve a good imaging effect.

EXAMPLE five

Referring to fig. 9, the optical system 100 in this embodiment includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and a filter L8, which are sequentially disposed from an object side to an image side along an optical axis H, a stop ST is disposed between an image side surface S2 of the first lens L1 and an object side surface S3 of the second lens L2, and an imaging surface IMG of the optical system 100 is located on a side of the filter L8 away from the seventh lens L7. The first lens L1 to the seventh lens L7 are all plastic aspheric lenses, and the filter L8 is an infrared cut filter L8 made of glass.

The first lens element L1 with positive refractive power has a convex object-side surface S1 at a paraxial region H, a concave image-side surface S2 at a paraxial region H, and a convex object-side surface S1 and an convex image-side surface S2 of the first lens element L1.

The third lens element L3 with negative refractive power has a concave object-side surface S5 and an concave image-side surface S6 at paraxial region H of the third lens element L3, and has a concave object-side surface S5 and a concave image-side surface S6 at periphery of the third lens element L3.

The sixth lens element L6 with positive refractive power has a convex object-side surface S11 at a paraxial region H and a concave image-side surface S12 at a paraxial region H of the sixth lens element L6, and has a concave object-side surface S11 and a convex image-side surface S12 at a circumference of the sixth lens element L6.

The seventh lens element L7 with positive refractive power has a convex object-side surface S13 at the paraxial region H and a concave image-side surface S14 at the paraxial region H of the seventh lens element L7, and has a concave object-side surface S13 and a convex image-side surface S14 at the periphery of the seventh lens element L7.

In the fifth embodiment, the focal length, refractive index and abbe number of the optical system 100 are all referenced to the light ray with the wavelength of 587.00nm, and the relevant parameters of the optical system 100 are shown in table 13. Where f is the effective focal length of the optical system 100, FNO represents the aperture value, FOV represents the maximum field angle of the optical system 100, TTL represents the total optical length of the optical system 100, and the units of the curvature radius, thickness, and focal length are all millimeters.

Watch 13

The numerical relationship calculation results of the parameters of the optical system 100 in the present embodiment are shown in table 14.

TABLE 14

As can be seen from the results in table 14, the calculation results of the numerical relationships between the lens-related parameters of the optical system 100 in the present embodiment satisfy the conditional expressions (1) to (8) in a one-to-one correspondence.

The conic constant K and aspherical surface coefficients corresponding to the surfaces of the respective lenses in example five are shown in table 15.

Watch 15

Fig. 10 (a), 10 (B), and 10 (C) are a longitudinal spherical aberration chart, an astigmatism chart, and a distortion chart, respectively, in the fourth example.

The abscissa of the vertical spherical aberration graph represents the focus shift and the ordinate represents the normalized field of view, and when the wavelengths given in (a) of fig. 10 are 650.0000nm, 610.0000nm, 587.0000nm, 555.0000, and 470.0000, respectively, the focus shifts of different fields of view are all within ± 0.025 mm, which illustrates that the optical system 100 in this embodiment has a small vertical spherical aberration and good imaging quality.

The abscissa of the astigmatism graph indicates the focus offset, the ordinate indicates the image height, and the astigmatism curve given in (B) of fig. 10 indicates that the focus offsets of the sagittal image plane and the meridional image plane are within ± 0.20 mm at a wavelength of 587.0000nm, which indicates that the optical system 100 in this embodiment has less astigmatism and better imaging quality.

The abscissa of the distortion graph represents the distortion rate, the ordinate represents the image height, and the distortion curve given in (C) of fig. 10 represents that the distortion is within ± 5% at a wavelength of 587.0000nm, which shows that the distortion of the optical system 100 in this embodiment is better corrected and the imaging quality is better.

As can be seen from fig. 10 (a), 10 (B), and 10 (C), the optical system 100 according to the fifth embodiment can achieve a good imaging effect.

EXAMPLE six

Referring to fig. 11, the optical system 100 in this embodiment includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and a filter L8, which are sequentially disposed from an object side to an image side along an optical axis H, a stop ST is disposed between an image side surface S2 of the first lens L1 and an object side surface S3 of the second lens L2, and an imaging surface IMG of the optical system 100 is located on a side of the filter L8 away from the seventh lens L7. The first lens L1 to the seventh lens L7 are all plastic aspheric lenses, and the filter L8 is an infrared cut filter L8 made of glass.

The first lens element L1 with negative refractive power has a concave object-side surface S1 at a paraxial region H and a convex image-side surface S2 at a paraxial region H of the first lens element L1, and has a convex object-side surface S1 and a concave image-side surface S2 at a circumference of the first lens element L1.

The fourth lens element L4 with negative refractive power has a convex object-side surface S7 at the paraxial region H and a concave image-side surface S8 at the paraxial region H of the fourth lens element L4, and has a concave object-side surface S7 and a concave image-side surface S8 at the periphery of the fourth lens element L4.

In the sixth embodiment, the focal length, refractive index and abbe number of the optical system 100 are all referenced to light with a wavelength of 587.00nm, and relevant parameters of the optical system 100 are shown in table 16. Where f is the effective focal length of the optical system 100, FNO represents the aperture value, FOV represents the maximum field angle of the optical system 100, TTL represents the total optical length of the optical system 100, and the units of the curvature radius, thickness, and focal length are all millimeters.

TABLE 16

The numerical relationship calculation results of the parameters of the optical system 100 in the present embodiment are shown in table 17.

TABLE 17

As can be seen from the results in table 17, the calculation results of the numerical relationships between the lens-related parameters of the optical system 100 in the present embodiment satisfy the conditional expressions (1) to (8) in a one-to-one correspondence.

The conic constant K and aspherical surface coefficients corresponding to the surfaces of the lenses in example six are shown in table 18.

Watch 18

Fig. 12 (a), 12 (B), and 12 (C) are a longitudinal spherical aberration graph, an astigmatism graph, and a distortion graph, respectively, in the first embodiment.

The abscissa of the vertical spherical aberration graph represents the focus shift and the ordinate represents the normalized field of view, and when the wavelengths given in (a) of fig. 12 are 650.0000nm, 610.0000nm, 587.0000nm, 555.0000, and 470.0000, respectively, the focus shifts of different fields of view are all within ± 0.025 mm, which indicates that the optical system 100 in the present embodiment has a small vertical spherical aberration and good imaging quality.

The abscissa of the astigmatism graph indicates the focus offset, the ordinate indicates the image height, and the astigmatism curve given in (B) of fig. 12 indicates that the focus offsets of the sagittal image plane and the meridional image plane are within ± 0.03 mm at a wavelength of 587.0000nm, which indicates that the optical system 100 in this embodiment has less astigmatism and better imaging quality.

The abscissa of the distortion graph represents the distortion rate, the ordinate represents the image height, and the distortion curve given in (C) of fig. 12 represents that the distortion is within ± 5% at a wavelength of 587.0000nm, which shows that the distortion of the optical system 100 in this embodiment is better corrected and the imaging quality is better.

As can be seen from fig. 12 (a), 12 (B), and 12 (C), the optical system 100 according to the sixth embodiment can achieve a good imaging effect.

As shown in fig. 13, some embodiments of the present application further provide a lens module 200, where the lens module 200 includes a photosensitive element 210, and the optical system 100 and the filter L8 of the optical system 100 as above. The photosensitive element 210 is disposed on the image side of the optical system 100 to receive light rays of an image formed by the optical system 100. The photosensitive element 210 may be a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). When assembled, the imaging surface IMG of the optical system 100 overlaps the photosensitive surface 211 of the photosensitive element 210.

As shown in fig. 14, in some embodiments of the present application, an electronic device 300 is further provided, and the lens module 200 is applied to the electronic device 300 to enable the electronic device 300 to have a lens function. Specifically, the electronic device 300 includes a fixing member 310 and the lens module 200 as above, and the lens module 200 is mounted on the fixing member 310 for capturing an image. The fixing member 310 may be a circuit board, a middle frame, a protective case, or the like. The electronic device 300 may be, but is not limited to, a smart phone, a smart watch, an electronic book, a reader, a vehicle-mounted lens device, a monitoring device, a medical device, a tablet computer, a biometric device PDA (Personal Digital Assistant), an unmanned aerial vehicle, and the like. Taking the electronic device 300 as a mobile phone as an example, the lens module 200 can be installed in a housing of the mobile phone, as shown in fig. 14, which is a front view of the lens module 200 installed in the housing of the mobile phone.

The same or similar reference numerals in the drawings of the present embodiment correspond to the same or similar components; in the description of the present application, it is to be understood that if there is an orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", etc. based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not intended to indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and are not to be construed as limitations of the present patent, and specific meanings of the above terms may be understood by those skilled in the art according to specific situations.

The present invention is not intended to be limited to the particular embodiments shown and described, but is to be accorded the widest scope consistent with the principles and novel features herein disclosed.

Claims

1. An optical system comprising seven lenses in order from an object side to an image side along an optical axis, comprising: a first lens element with refractive power;

a third lens element with refractive power;

a fourth lens element with refractive power;

the optical system satisfies the conditional expression: 1.0 < | R11/R22 |. FNO < 1.56 and 0 < SAG62/R62 < 0.55, wherein R11 is the radius of curvature of the object-side surface of the first lens at the optical axis, R22 is the radius of curvature of the image-side surface of the second lens at the optical axis, FNO is the f-number of the optical system, SAG62 is the rise of the image-side surface of the sixth lens at the maximum clear aperture, and R62 is the radius of curvature of the image-side surface of the sixth lens at the optical axis.

2. The optical system according to claim 1, further comprising a diaphragm, the optical system satisfying the conditional expression: 0 < ET12 × SD11 < 0.16, wherein ET12 is the distance from the maximum clear aperture of the image side surface of the first lens to the diaphragm along the direction parallel to the optical axis, and SD11 is the maximum effective half aperture of the object side surface of the first lens.

3. The optical system according to claim 1, wherein the optical system satisfies the conditional expression: and 2.4 < TTL/f FNO < 2.8, wherein TTL is the distance from the object side surface of the first lens to the imaging surface of the optical system on the optical axis, and f is the effective focal length of the optical system.

4. The optical system according to claim 1, wherein the optical system further satisfies the conditional expression: 0.75 < f67/f < 3.75, wherein f67 is a combined focal length of the sixth lens and the seventh lens, and f is an effective focal length of the optical system.

5. The optical system according to claim 1, wherein the optical system satisfies the conditional expression: 0.45 < (ET34+ ET45+ ET56+ ET67)/FFL < 1.15, wherein ET34 is the distance in the direction parallel to the optical axis between the maximum clear aperture position of the image side surface of the third lens and the maximum clear aperture position of the object side surface of the fourth lens, ET45 is the distance in the direction parallel to the optical axis between the maximum clear aperture position of the image side surface of the fourth lens and the maximum clear aperture position of the object side surface of the fifth lens, ET56 is the distance in the direction parallel to the optical axis between the maximum clear aperture position of the image side surface of the fifth lens and the maximum clear aperture position of the object side surface of the sixth lens, ET67 is the distance in the direction parallel to the optical axis between the maximum clear aperture position of the image side surface of the sixth lens and the maximum clear aperture position of the object side surface of the seventh lens, and FFL is the shortest distance in the direction of the optical axis between the image side surface of the seventh lens and the imaging surface of the optical system.

6. The optical system according to claim 1, wherein the optical system satisfies the conditional expression: 0.04 < | R21/R32| < 0.38, wherein R21 is a radius of curvature of an object-side surface of the second lens at an optical axis, and R32 is a radius of curvature of an image-side surface of the third lens at the optical axis.

7. The optical system according to claim 1, wherein the optical system satisfies the conditional expression: 0.35 < | f3/R32| < 1.18, wherein R32 is a radius of curvature of an image-side surface of the third lens at an optical axis, and f3 is a focal length of the third lens.

8. A lens module, comprising:

the optical system of any one of claims 1 to 7; and

and the photosensitive element is arranged on the image side of the optical system.

9. An electronic device, comprising:

a fixing member; and

the lens module as recited in claim 8, wherein the lens module is mounted to the fixing member.